Boyz Doc

Dr Laura Waters from Mortimer Market Centre on ‘I’ve just been diagnosed – so what’s viral load?’

Dear Dr Laura,

I’m 26 and I was diagnosed HIV about 6 weeks ago. My clinic has put me straight on to treatment but I was wondering what is viral load? And why is it important? The doctor said mine was 10,000. Many thanks.


Dear Sam,

Thank you for your question. The viral load is a measure of how much HIV is in your blood. It’s measured in ‘copies per millilitre’ i.e. how many virus particles are in each millilitre of your blood. The test is important for three main reasons:

  • To decide which treatment to start
  • To monitor treatment
  • To guide the risk of transmission

Some HIV drugs work less well at high viral loads, usually defined as more than 100,000; in this case we would avoid those drugs (though it’s fine to switch to them once the viral load has come down). At 10,000 your viral load is pretty low which means any suitable drug combination can be used.

A key goal of HIV treatment is to get the blood virus down to undetectable levels, meaning the virus level is too low to be picked up on the test. Depending on the test your clinic does this might be reported as less than 50, 40 or 20 copies. Viral load is the important test for checking your HIV treatment is working. Because you started treatment with a low viral load you should be undetectable quickly, maybe within a month.

If the virus doesn’t go down on treatment, or bounces up from undetectable, it’s important to find out why. The main reasons are:

  • Missing doses
  • Not following instructions (e.g. some medications should be taken with food and if you don’t food the drug levels may be too low to keep the virus undetectable)
  • Taking other medications that interact with your HIV meds (e.g. rilpivirine, which is in drugs Eviplera, Odefsey, Edurant and Juluca, can’t be taken with some indigestion treatments as they cause much lower levels of rilpivirine in the blood).

Once the virus is undetectable on treatment then U=U comes into play! U=U stands for undetectable = untransmittable meaning, if you are on HIV treatment with an undetectable viral load there is ZERO RISK OF PASSING HIV ON TO YOUR SEXUAL PARTNERS!

People with detectable virus can pass the virus on and the higher the viral load, the higher the risk. It’s common to have a very high viral load (in the millions) during very early HIV and this is when the transmission risk is highest. The viral load usually settles after a few months, typically to a level in the tens of thousands, but these days that’s not really relevant as we offer treatment to everyone straight away – as your clinic did for you.

A few years back we waited until your immune system (measured by your CD4 count) fell before we started medication but now, thanks to good evidence that early treatment is good for your health, plus the great news about U=U, that’s no longer a consideration.

To enjoy the benefits of an undetectable viral load (good health, normal life expectancy and zero transmission risk) you need to take your medications regularly, as instructed by your clinic.

It’s important to find a combination that suits you and your lifestyle, with no or minimal side-effects (side-effects are one of the commonest reasons to miss doses). Phone reminders can help and I usually recommend taking meds in the morning since this tends to be a fairly predictable part of the day – once taking tablets, alongside brushing your teeth, or your morning coffee, becomes habit you’re less likely to forget.

As well as the risk of transmission, if your viral load goes up on treatment there’s a risk of developing resistance to your medication. If you do miss doses tell the clinic since resistance is less likely on some combinations than others.

Once you’re stable on treatment most clinics check your viral load every 6 months and as long as you take your meds correctly your viral load should stay undetectable for life! 

You can read more about viral load here:

The Boyz Doc is Dr Laura Waters, an HIV and sexual health consultant at the Mortimer Market Centre in central London. Dr Laura answers your questions every week in Boyz. If you have a question for Dr Laura please email her at [email protected]


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